Adverb
Always; throughout; as, sempre piano, always soft.
Source: Webster's dictionaryAlors sempre avanti! (Ever Forward / Always Ahead) Wassily Kandinsky
But in comparison with every other work of the composer, it is wanting in tunes of a broad and impressive character, and one or two of the type of "O Mia Regina", "Ritorna Vincitor", or "Ora per sempre addio" might have helped the situation. Source: Internet
The concluding ensemble delivers the moral of the opera – "Such is the end of the evildoer: the death of a sinner always reflects his life" ("Questo è il fin di chi fa mal, e de' perfidi la morte alla vita è sempre ugual"). Source: Internet
It is also used, mainly amongst the young people, as a short written form for "per", meaning "for": for example, "x sempre" ("forever"). Source: Internet